to_io_select.rb

class Connection
  # .. rest of the class .. #

  def accept_connection(io)
    @io = io

    # new connection code
  end

  def to_io
    @io
  end
end 

class Reactor
  # array_of_connections_to_read is an array of instances of the above Connection class
  # array_of_connections_to_write is an array of instances of the above Connection class

  def tick
    to_read, to_write = IO.select(array_of_connections_to_read, array_of_connections_to_write)
  end
end